Contact bank for an automatic telephone switch including parallel elongated stationary conductors



July 25, 1950 G T B KER 2 516,745

. A CONTACT BANK FOR AN AUTOMATIC TELEPHONE SWITCH INCLUDTNG PARALLEL ELONGATED STATIONARY CONDUCTORS Original Filed March 6, 1943 5 Sheets-Sheet l INVEN TOR. GEORGE THOMAS BAKER ATTORNEY July 25, 1950 G. T. BAKER CONTACT BANK FOR AN AUTOMATIC TELEPHONE swrrcn INCLUDING PARALLEL ELONGATED STATIONARY CONDUCTORS Original Filed March 6, 1943 3 Sheets-Sheet 2 INVENTOR. GEORGE moms BAKER ATTORNEY July 25, 1950 G T BAK R 2,516,745

E CONTACT BANK FOR AN AUTOMATIC TELEPHONE SWITCH INCLUDING PARALLEL ELONGATED STATIONARY CONDUCTORS Original Filed March 6, 1945 3 Sheets-Sheet 3 R w T V 7 n T O J 2; FIG. 5 2O *7 N 3 I8 I If I6 22 ZS f fyf r. M iii if: A: j:

2 24 IS F 2|\ INVENTOR.

GEORGE THOMAS BAKER ATTORNEY ,Patented July 25, 1950 CONTACT BANK FOR AN AUTOMATIC TELE- PHONE SWITCH INCLUDING PARALLEL ELONGATED STATIONARY CONDUCTOR/S George Thomas Baker, Liverpool, England, as-

signor to Automatic Electric Laboratories, Inc., Chicago, 111., a corporation of Delaware Original application March 6, 1943, Serial No. 478,241. Divided and this application January 12, 1946, Serial No. 640,786. In Great Britain April 20, 1942 9 Claims.

The present invention concerns the construction of contact banks for selector switches as used in automatic telephone systems and is more particularly directed to a contact bank construction which permits of a number of contact banks for different switches being made in a single unit. This application is a division of my copending application Serial N 0. 478,241, filed March 6, 1943, now Patent No. 2,435,025, dated January 2'7, 1948.

The contact banks according to the invention are generally distinguished from the more usual form adopted for automatic telephone systems in that instead of consisting of fixed contact members which are selectively engaged by the movement of a common wiper or brush forming the movable contact, they consist of both fixed contact members and movable contact members, the movable contact members of a switch being individually associated with fixed contact members and adapted to be deflected so as to engage with the fixed contact member. It is to be understood that the expression fixed contact member or fixed conductors is not intended to imply that the contact or conductor is immovable but that it is not directly moved bythe switch operating members; it may be deflected from its normal position by pressure exerted thereon by a movable contact member or conductor.

According to one feature of the invention a contact bank for a plurality of switches comprises a number of fixed conductors parallel to each other; bounding planes normal to the conductors and corresponding to the limits of each switch in the direction of the said conductors allocate a part of each of said fixed conductors to a switch, and movable conductors one for each of said parts of each fixed conductor are arranged to make contact with the fixed conductors at substantially the same relative positions in each switch with respect to the bounding planes thereof, the movable conductors being arranged in pairs between adjacent fixed conductors so that they must be moved in opposite directions to make contact with the fixed conductors.

According to a further feature of the invention the fixed conductors are formed by punching or cutting from a blank or blanks of metal on which contact material is rolled so as to be secured thereto in regularly spaced strips, the spacing corresponding to the distance between corre- 2 sponding parts of adjacent switches whereby contact material is obtained at the points where the fixed and movable conductors engage.

The invention will be better understood from the following description of one method of carrying it into elfect, reference being had to the accompanying drawings which correspond to similar figures in my copending application Serial No. 478,245, filed March 6, 1943, now Patent No. 2,402,232, granted June 18, 1946.

Referring now to the drawings, Fig. 1 shows a perspective part view of a rectilinear continuous bank showing the metal strip multiples and the precious metal. contacts, desired connection being effected by the appropriate operation of cordless contact operating members conveniently referred to hereinafter as wiper arms,

Fig. 2 shows a perspective part View of the clamping and supporting arrangements for the rectilinear continuous bank of Fig. 1,

Fig. 3 shows a plan view of a precious metal contacted comb plate as it is being stamped from a metal sheet which is edged with precious metal,

Fig. 4 shows how the continuous metal strip multiples are stamped from a suitable metal sheet on which precious metal contact strips have been rolled, and

Fig. 5 shows a part elevational View of the rectilinear continuous bank and showing in detail an end view of part of a level, while Fig. 5a shows a corresponding plan view.

A bank is formed by continuous strips 23 running the full length of the predetermined multiple and as shown in the part view Of Fig. l and Figs. 5 and 5a these are clamped at opposite sides of selectors, to form fixed contact members, the intervening space between the clampings forming the bank contacts for one selector. At the end of the multiple it will be understood that the strips 23 are fanned out to form wiring tags. That part of the bank multiple allocated per selector will subsequently be referred to as a selector bank so that Fig. 1 may be described as showing a part view of two selector banks in each of which are included three levels of two conductors each. A level of one bank is moreover assumed to have been broken away in order more closely to illustrate its construction. Each bank will be preferably of the point type, that is to say, with ten levels of ten sets of contacts,

each set of four contacts being formed on four strips and four combs 24; on each level there will be provided in addition the usual eleventh step set of contacts 25 for overflow busy indication purposes.

A multiple will usually comprise twenty such banks assembled together one above the other, the necessary multipling being inherently per formed by virtue of the use of the continuous strips 23 which connect with the outgoing trunks.

The connecting function of the ordinary selector wipers and cords is taken by a set of comb plates 2% one of which is provided for each row of strips, conveniently referred to as a level, of

each bank and having fingers 26 aligned with the various bank strips.

Each finger of a comb what manner the same is to be performed, I deplate such as 24 forms a movable contact member. All bank contacts are made of precious metal such as silver, and to make this a commercial proposition all the silver-base-metal junctions are made by rolling, this rolling operation being carried out in the stock before blank- The continuous strips are stamped from a meta1. sheet, such as it (Fig. 4) the width of which sheet equals the length of strip required. On this sheet silver contact strips will have been previously rolled at right angles to the direction of the trunk strips (as shown) and at spacings of say 1% inches, this distance representing the calculated vertical distance required between bank centres to accommodate the selector switches one above another. The comb plates are stamped fioin springy metal ribbon ll (Fig. 3) of suitable width and provided with a rolled silver edgeof, say, about 26 mils width. The comb plate finers are preferably each split with a sawout (not shown) to give a twin contact efiect and the plates are subsequently formed to give the requisite shape shown in Figs. 1 and 5.

Each row of contact members in a bank is separated from its neighbour by an insulating plate such as l2 (Figs. 5 and 5a) of a length equa1 to that of the comb plates and of a thickness of say 50 mils to reduce possible cross talk to a minimum and at the same time to give ample room in the level for the insertion of the wiper arms. Since each trunk strip will be clamped in each of the twenty banks through which they pass, it is not considered necessary to provide clamping bars which extend through the banks, and accordingly it will be seen that each bank of the multiple after assembly in a suitable jig will be clamped together by two horizontal clamp plates [3 and [4' (Figs. 2, 5 and 5a) which are secured against the bank by clamp rods [5 and Hi. The requisite spacing of 1 inches between adjacent banks is secured by means of the four vertical members 17,18, is and 2B which extend over the length of the multiple and which are secured at 5 each bank by the two clamp rods provided individual thereto. As is described in the abovementioned application Serial No. 478,245, each selector switch mechanism is adapted to jack into position against its bank with its wiper arms nor- [9 and 2D and the adjacent clamp bar I4. Clamp rod is which will be nearest to the selector switch mechanism when the latter is in position will be ofsuoh a length as to finish ofi level with the vertical members IT and I9 including its fixing.

nuts or screws. The other clamp rod [6 will be clare that what I claim is:

1. An electrical contact bank, comprising a plurality of groups of elongated stationary conductors, all of said conductors being parallel and each group thereof occupying a plane parallel to the plane's occupied by the other groups, each group of stationary conductors having associated therewith a plurality of groups of movable conductors, each of said last groups including a different independently movable conductor for each stationary conductor in the associated group of stationary conductors, means supporting the different groups of movable conductors at regularly spaced intervals along the length of said stationary conductors so that the movable conductors of each group normally are aligned with one an other in a direction transverse to the length of said stationary conductors and parallel to said planes, each movable conductor being proximate toits individual stationary conductor and movable into engagement therewith.

2. An electrical contact bank, comprising a plurality of parallel elongated stationary conductors, a plurality of groups of movable conductors, each group. including a difierent movable conductor for each stationary conductor, and means supporting the different groups of movable conductors at regularly spaced intervals alongthe length of said stationary conductors, the movable conductors of each group being arranged in pairs between adjacent ones of said stationary conductors, whereby the conductors of each pair are movable in opposite directions to make electrical contact with their respective individual stationary conductors.

3. An electrical contact bank, comprising a plurality of groups of elongated primary conductors, all of said conductdrs being parallel and each group thereof occupying a plane parallel to the planes occupied by the other groups, a pluralit'y of groups of secondary conductors, each of said" secondary conductors being transverse to the length of said primary conductors and each group of secondary conductors being substatitially in a plane parallel and adjacent to the plane occupied by a particular group of primary conductors, each secondary conductor having different integral portions corresponding respectively to different primary conductors in the adj acent group, and each said portion being independntly movable into and out of engagement with its respectively corresponding primary conducton.

4. An electrical contact bank as claimed in claim 3, wherein each of said secondary conductors is generally comb-shaped; and wherein the teeth ofcach comb are independently movable into and outof engagement with the respec-i tively corresponding primary conductors. v

(.5. {in electrical. contact bank, comprisinga plurality of elongated base metal conductors,

g each conductor having thereon a plurality of precious metal contacts situated at spaced apart intervals along the length of such conductor, means supporting said elongated conductors parallel to one another so that the contacts are situated in rows running transverse to the length of said conductors, a movable conductor individual to each of said precious metal contacts, said movable conductors situated in rows parallel to said elongated conductors and to said rows of contacts and each being movable into engagement with its individual contact.

6. An electrical contact bank comprising a plurality of parallel elongated stationary conductors, a plurality of groups of movable contactors, each group including a different movable contactor for each stationary conductor, and means supporting the different groups of movable contactors at regularly spaced intervals along the length of said stationary conductors so that each movable contactor is adjacent its individual stationary conductor and is movable into engagement therewith, said supporting means for each group comprising a single insulator common to the contactors of that group and also common to all of said stationary conductors, and said insulators interposed between said movable contactors and said stationary conductors to maintain them spaced apart.

'7. An electrical contact bank comprising a plurality of parallel elongated stationary conductors, a plurality of groups of movable contactors, each group including a different movable contactor for each stationary conductor, the movable contactors of each group comprising separately deflectable projections extending from an integral base member common to said projections, and means supporting the different groups of movable contactors at regularly spaced intervals along the length of said stationary conductors so that each movable contactor is adjacent its individual stationary conductor and is positioned for movement into engagement therewith.

8. An electrical contact bank comprising a pinrality of parallel elongated stationary conductors, said conductors comprising strips of metal having a generally rectangular transverse cross section, a plurality of groups of movable contactors, each group including a different movable contactor for each stationary conductor, and means supporting the different groups of movable contactors at regularly spaced intervals along the length of said stationary conductors so that each movable contactor is adjacent its individual stationary conductor and is positioned for movement into engagement therewith.

9. An electrical contact bank comprising a plurality of parallel elongated stationary conductors, a plurality of spaced apart precious metal contact surfaces on said conductors, a plurality of groups of movable contactors, each group including a different movable contactor for each stationary conductor, the movable contactors being arranged in pairs between adjacent ones of said stationary conductors, and means supporting said movable contactors so that the contactors of each pair are positioned for movement in opposite directions to make electrical contact with their respective individual stationary conductors at the point of said precious metal contact surfaces.

GEORGE THOMAS BAKER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,523,407 Dobbin Jan. 20, 1925 2,120,980 Johnston June 21, 1938 2,261,412 Reeve Nov. 4, 1941 2,279,811 Baker Apr. 14, 1942 2,360,063 Larson Oct. 10, 1944 

